OSTEOLOGY. 



19 



The lower surface presents : 



Rostrum, the continuation downward of the ethmoidal crest, 

 for articulation with the alae of the vomer; 



Vaginal processes, a thin plate of bone on either side articu- 

 lating with the edges of the vomer ; and 



Groove, converted into the ptery go-palatine canal by articu- 

 ] -it ion with the sphenoidal process of the palate bone for trans- 

 mission of the pharyngeal nerve and pterygo-palatine vessels. 



The anterior surface presents : 



Ethmoidal crest, a thin plate of bone articulating with the 

 ethmoid ; 



Openings of sphenoidal cells or sinuses partially closed by 

 the sphenoidal turbinated bones or pyramids of Wistar, two 

 curved plates of bone absent in infancy but derived as a pair 

 of cones from the ethmoid. The sphenoidal cells open into the 



FIG. 10. 



1, tensor palati; 2, Vidian canal; 3, pterygoideus interims; 4, 

 pterygo-palatine canal; 5, vaginal process; 6, superior constrictor of 

 pharynx; 7, scaphoid fossa; 8, pterygoid fossa. 



superior meatus of the nose, but occasionally into the posterior 

 ethmoidal sinuses. 



Tho jioslcrior surface articulates with the basilar process of 

 the occipital and becomes united to it between the eighteenth and 

 twenty-fifth year. 



GREATER WINGS OF THE SPHENOID. 



The superior surfaces of the great wing, deeply concave, 

 forms part of middle fossa of skull and presents the following : 



Foramen rotundum, for second division of fifth nerve; fora- 

 men ovale, for third division of fifth, small meningeal artery, 

 and small petrosal nerve; font men Vesalii, for small vein, and 

 fora in i' n x{)i}iosum, for passage of middle meningeal artery. 



Tin- exterior surfnrr is convex and presents: 



Pterygoid ridge, dividing the bone into two portions; 



